PDA

View Full Version : '94 6.5L K2500 speedometer jumping/pegging?



dbryans
02-07-2005, 10:44
I've been searching through the archives for information, but haven't yet found the same set of conditions that cause my speedometer problems.

I'm driving a '94 Chevy K2500 Suburban with the 4L-80E.

My speedometer will begin to jump up 30+ MPH, or simply peg to the pin (85+), but only on a warm engine.

As other have noted, it does not affect cruise control, or transmission shifts (not that I can tell). I can usually make it go back to normal for a few seconds if I back off on the accelerator, or apply the brakes.

I 'm new to this truck, only owned it for about a month, and the previous owner was aware of the problem and I was informed prior to purchase. It didn't really bother me, until I started towing out travel trailer this weekend and realized I couldn't regulate my speed like I needed to due to the speedometer being pegged.

Here is some more info on what the previous owner has commented on the subject:

Anyway, when I began noticing problems was when I replaced the four wheel drive actuator. Or at least shortly thereafter. It is located on the front axle, and if you are lying on the ground looking up at it, it screws into the axle housing from the passenger side, and looks like little more than a nut with some wires coming off of it. It has a bit of pink paint on it that sets it off a little. That was the way it came. Anyway, the original apparatus that failed had three plugs on it, and the replacement (more effective version) uses only one. The other two pigtails are simply zip tied to the axle housing. There is probably a much better solution for that, but I never pursued it, and here we are today. I am pretty sure that if someone who knows electronics better than us started there, that they would find a solution shortly.I'm not a mechanic, but not afraid to get dirty and like to do stuff myself, but could use a few hints on where to start.

The local dealer just want to replace the whole gage console assembly for $450! It sounds like it may just be a loose ground but really don't know where to start.

Thanks for your ideas and this great forum.

Shane...

dbryans
02-07-2005, 22:31
Well, call me a liar, but wouldn't you know it, I started up after work (8+ hours idle in 40-50F slightly overcast day) and I had the jumping speedometer again. This time the engine was "cold", albeit not a really cold day.

Also noted today that when the wipers are turned on/off or lights and blinkers are turned on/off, I get a brief normal reading on the speedometer, then back to the peg.

It's sounding more like a ground short I guess.

Shuck
02-07-2005, 23:52
I just bought a 95 K1500 truck that does the same thing. Seems to happen more often when the truck is cold, though. I also notice that my tach jumps with the speedo. I also have noticed that the transmission selection indicator light will dim out for a bit. Anyone else seen this?

dbryans
02-08-2005, 08:29
In my case, no tachometer movement in correspondence to the speedometer jumping. I have notice every once in a while (rarely) that the trip odometer willl tick over a few tenths when sitting and idling, in park or in gear and w/ or w/out the brake applied. It's very infrequent, like three times that I've noticed it over the last month of daily driving.

Shane...

kevin77
02-08-2005, 17:57
my insturments, tach, speed would occasionally go nuts - I found out that the battery cable connecting the positive between batteries was rubbing on the front of the AC compressor. There was a flat spot worn done to bare copper.

It explained several electrical quirks that I had...

Kevin

BrentN
02-09-2005, 11:12
Check your grounds from the harness to the block. This problem plagued me on a 93 Burb 5.7L gas for nearly a year. It was a loose nut on a stud off of the intake manifold where the fuel injection harness grounds to. Not sure the exact location on our 6.5's..But since the speed sensor goes through the computer...the grounds have to be really good. Also check your negative battery connection as well as the ground strap to body.

Let me know if you need any more help. Brent